I'm a student, just getting started with Oracle, and my teacher is not very helpful with the install/running problems that I'm having with Oracle.

I installed Oracle 11g Express a week ago, and upon installing it, the software worked just fine. I was able to create connections and write basic select statements to get data from a database provided by the manufacturer of my textbook.

Now, when I try to connect to the database, I get an error that says "ORA_12528, TNS:listener: all appropriate instances are blocking new connections."

I did a little research on how to fix this, and got into the listener to see its status. Here's what it says:

After doing more googling, I found someone suggested that logging on to SQL*Plus as sysdba and then shutting down and restarting the database might do something to fix this, but when I try to log in it doesn't work... here's what I see in SQL*Plus:

I have no idea what's going on here, and unfortunately, since I'm a student and have just started with Oracle, I can't seem to make heads or tails of most of what I'm finding on the forums here (and most of the threads that seem pertinent are 6 or more years old).

If anyone out there can help me, I'd greatly appreciate it! Thanks in advance!

I started the DB before doing what you suggested. According to my computer, after entering "net start OracleServiceXE" the service was started successfully. Then I tried what you suggested and here's what I got:

I did take a look at the link you posted and I tried to do what it said, but I don't really know what to make of what I found. When I run services.msc I find the following are running:
OracleJobSchedulerXE, OracleMTSRecoveryService, OracleServiceXE, OraclexEClrAgent, and OracleXETNSLisnener
So it appears that the Oracle Service is running... probably not the problem.

With regards to the logs, I don't know how to do what you suggested (make the log bigger, allow for overwrites, etc.).

I tried to follow the suggestions from the link you posted and get into the event viewer, but when I enter "eventviewer" in the run window my machine can't find it. I tried other methods I found online to get into the event viewer, but it appears as though my computer doesn't offer me access to it (or simply doesn't have that capability). Are there other ways to clear old logs? Can I just open it as a text file and delete the contents? I don't want to make a mess out of things, and I really don't know what I'm doing so any guidance would be appreciated.

Please identify your exact OS version. On my Windows XP machine, I use Start > Control Panel > Administrative Tools > Event Viewer, then single left-click the Application (or System) log to select it, then single right-click and select Properties, and can adjust the properties and size on the resulting window.

If you are now able to connect "/ as sysdba" as you demonstrated, the issue may have been resolved (or resolved itself). Are you now able to use the database/application ?

I have been searching for this fix for almost a day, simply I had XE running on my WinXP computer for days with no issue. I was under the impression the issue was because my IP changed and spent alot of time in the tns area. All I did was clear the windows event logs stopped all services and restarted and I was ready to throw my computer thru the window, why the heck do they make things so difficult, thanks for taking the time for this post@